Load script in README

[seandenigris]

The current script is very cool!

That said, it may throw seasoned Pharo-ers of because the style is so unusual. I assume it's a functional style? IMHO it may be better to show that off elsewhere giving the context to understand what the point is. A more traditional script would be:

Metacello new
	baseline: 'SmalltalkVimMode';
	repository: 'github://unchartedworks/SmalltalkVimMode';
	onConflict: [ :ex | ex allow ];
	load.

NB: also notice that #get isn't needed because it's included in #load